Dutch research suggests low levels of the chemicals are found in food from the environment or packaging.

However, some scientists have questioned whether the small quantities involved present a danger to health.

We should not be complacent about the presence of these chemicals in foods and should keep trying to reduce the levels

Professor Alan Boobis, of Imperial College London

The Dutch scientists found low levels of pesticides, flame retardants, non-stick chemicals, artificial musks used to scent products and phthalate chemical compounds used in plastics were present in food.

Further research at the London School of Pharmacy suggests low doses can work together to produce a significant combination.

Tests on animals and human cells show they might be a factor in various serious medical conditions.

Paul King, director of campaigns for WWF-UK, said: "While each item of food we tested is probably safe to eat on its own, taken together over long periods of time the food we eat contributes significantly to our body burden of chemicals."

The organisation is now calling for strict controls on the use of chemicals to be introduced by the European Parliament.

'Balanced view'

But Professor Alan Boobis, of Imperial College London, is among a number of toxicologists who have played down the research.

He said: "We should not be complacent about the presence of these chemicals in foods and should keep trying to reduce the levels.

"But we should also maintain a balanced view about whether these trace amounts represent a risk to the consumer and I don't believe that at these levels they represent a significant threat to human health"

And toxicologist Professor John Henry, of St Mary's Medical School, London, said WWF-UK was well intentioned but it had not demonstrated that the chemicals cause harm.

The Food Standards Agency and the chemical industry said levels of individual chemicals are not harmful but they are looking into how they add up in people's diets.

Steve Elliott, chief executive of the Chemical Industry Association, added the public should not be "overly concerned".

"I think there is a significant among of work that needs to be done to look at the additive effect in terms of how one substance might react with another and the ultimate product of that reaction."